The Impact of Power Weighted Mean Velocity on the Evaluation of Volumetric Flow in Small Vessels

1998 ◽  
Vol 31 (2) ◽  
pp. 336A
Author(s):  
H Becher
Keyword(s):  
Weighted Mean ◽  
Mean Velocity ◽  
Small Vessels ◽  
The Impact

scholarly journals The impact of power weighted mean velocity on the evaluation of volumetric flow in small vessels

1998 ◽  
Vol 31 ◽  
pp. 336
Author(s):  
H. Becher ◽  
K. Tiemann ◽  
J. Köster ◽  
T. Schlosser ◽  
B. Ludoritz
Keyword(s):  
Weighted Mean ◽  
Mean Velocity ◽  
Small Vessels ◽  
The Impact

scholarly journals Assessment of Soil Erosion and Its Impact on Agricultural Productivity by Using the RMMF Model and Local Perception: A Case Study of Rangun Watershed of Mid-Hills, Nepal

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Dinesh Bhandari ◽  
Rajeev Joshi ◽  
Raju Raj Regmi ◽  
Nripesh Awasthi
Keyword(s):  
Soil Erosion ◽  
Soil Loss ◽  
Group Discussion ◽  
Agricultural Productivity ◽  
Weighted Mean ◽  
Risk Area ◽  
Barren Land ◽  
Erosion Risk ◽  
Risk Areas ◽  
The Impact

Soil erosion is a major concern for the environment and natural resources leading to a serious threat to agricultural productivity and one of the major causes of land degradation in the mid-hills region of Nepal. An accurate assessment of soil erosion is needed to reduce the problem of soil loss in highly fragile mountainous areas. The present study aimed to assess spatial soil loss rate and identified risk areas and their perceived impact on agricultural productivity by using the Revised Morgan–Morgan–Finney (RMMF) model and social survey in the Rangun watershed of Dadeldhura district, Nepal. Soil erosion was assessed by using data on soil, digital elevation model, rainfall, land use, and land cover visually interpreted from multitemporal satellite images, and ILWIS 3.3 academic software was used to perform the model. A household questionnaire survey (n = 120) and focus group discussion (n = 2) in identified risk areas were carried out to understand the people’s perception towards soil erosion and its impact on agricultural productivity. The predicted average soil erosions from the forest, agriculture, and barren land were 2.7 t ha−1 yr−1, 53.73 t ha−1 yr−1, and 462.59 t ha−1 yr−1, respectively. The erosion risk area under very low to low, moderate to moderately high, and high to very high covers 92.32%, 4.96%, and 2.73%, respectively. It indicates that the rate of soil erosion was lower in forest areas, whereas it was higher in the barren land. The cropped area of the watershed has been reduced by 2.96 ha−1 yr−1, and productivity has been decreased by 0.238 t ha−1 yr−1. The impacts such as removal of topsoil (weighted mean = 4.19) and gully formation (weighted mean = 3.56) were the highest perceived factors causing productivity decline due to erosion. People perceived the impact of erosion in agricultural productivity differently ( ∗ significant at P ≤ 0.05 ). The study concluded that, comparatively, barren and agricultural lands seem more susceptible to erosion, so the long-term conservation and management investment in susceptible areas for restoration, protection, and socioeconomic support contribute significantly to land rehabilitation in the Rangun watershed.

scholarly journals Spatiotemporal droplet dispersion measurements demonstrate face masks reduce risks from singing: results from the COvid aNd FacEmaSkS Study (CONFESS)

2021 ◽  
Author(s):  
Kai Man Alexander Ho ◽  
Hywel Davies ◽  
Ruth Epstein ◽  
Paul Bassett ◽  
Aine Hogan ◽  
...  
Keyword(s):  
Regression Models ◽  
Sound Intensity ◽  
Face Mask ◽  
Multilevel Regression ◽  
Planar Imaging ◽  
Mean Velocity ◽  
Velocity Magnitude ◽  
Droplet Production ◽  
The Impact ◽  
Droplet Transmission

Background: COVID-19 has restricted singing in communal worship. We sought to understand variations in droplet transmission and the impact of wearing face masks. Methods: Using rapid laser planar imaging, we measured droplets while participants exhaled, said "hello" or "snake", sang a note or "Happy Birthday", with and without surgical face masks. We measured mean velocity magnitude (MVM), time averaged droplet number (TADN) and maximum droplet number (MDN). Multilevel regression models were used. Results: In 20 participants, sound intensity was 71 Decibels (dB) for speaking and 85 dB for singing (p<0.001). MVM was similar for all tasks with no clear hierarchy between vocal tasks or people and >85% reduction wearing face masks. Droplet transmission varied widely, particularly for singing. Masks decreased TADN by 99% (p<0.001) and MDN by 98% (p<0.001) for singing and 86-97% for other tasks. Masks reduced variance by up to 48%. When wearing a mask, neither singing task transmitted more droplets than exhaling. Conclusions: Wide variation exists for droplet production. This significantly reduced when wearing face masks. Singing during religious worship wearing a face mask appears as safe as exhaling or talking. This has implications for UK public health guidance during the COVID-19 pandemic.

scholarly journals Structural Alteration in Dermal Vessels and Collagen Bundles following Exposure of Skin Wound to Zeolite–Bentonite Compound

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Shahram Paydar ◽  
Ali Noorafshan ◽  
Behnam Dalfardi ◽  
Shahram Jahanabadi ◽  
Seyed Mohammad Javad Mortazavi ◽  
...  
Keyword(s):  
Healing Process ◽  
Volume Density ◽  
Skin Wound ◽  
Sprague Dawley ◽  
Small Vessels ◽  
Sprague Dawley Rats ◽  
Significant Difference ◽  
Sterile Normal Saline ◽  
Animal Skin ◽  
The Impact

Background. This study examines the impact of one-time direct application of haemostatic agent zeolite–bentonite powder to wounded skin on the healing process in rats. Materials and Methods. 24 male Sprague-Dawley rats were randomly allocated into two groups (n=12): (1) the rats whose wounds were washed only with sterile normal saline (NS-treated) and (2) those treated with zeolite–bentonite compound (ZEO-treated). The wound was circular, full-thickness, and 2 cm in diameter. At the end of the 12th day, six animals from each group were randomly selected and terminated. The remaining rats were terminated after 21 days. Just after scarification, skin samples were excised and sent for stereological evaluation. Results. The results showed a significant difference between the two groups regarding the length density of the blood vessels and diameter of the large and small vessels on the 12th day after the wound was inflicted. Besides, volume density of both the dermis and collagen bundles was reduced by 25% in the ZEO-treated rats in comparison to the NS-treated animals after 21 days. Conclusions. One-time topical usage of zeolite–bentonite haemostatic powder on an animal skin wound might negatively affect the healing process through vasoconstriction and inhibition of neoangiogenesis.

scholarly journals Endoscopic vein harvesting Impact of learning curve on results and rehabilitation

2005 ◽  
Vol 64 (2) ◽  
Author(s):  
Alessandro Piccardo ◽  
Luigi Martinelli ◽  
Giancarlo Passerone
Keyword(s):  
Learning Curve ◽  
Left Internal Mammary Artery ◽  
Consecutive Series ◽  
Short Term ◽  
Mean Velocity ◽  
Reliable Technique ◽  
Endoscopic Vein Harvesting ◽  
The Mean ◽  
The Impact ◽  
Vein Harvesting

Background: The tendency of modern surgery is towards the reduction of invasiveness. The aim of this study is to evaluate the impact of the learning curve, the reliability, the short term results and the advantages in terms of rapid rehabilitation of endoscopic vein harvesting (EVH) in a consecutive series of 20 patients operated on of aorto-coronary bypass surgery. Methods: Between February and June 2005, 20 patients between 61 e 82 years of age underwent EVH with the use of Vasoview® 5 (Guidant Corporation, Indianapolis, USA). To evaluate the impact of learning curve on the total operative time, patients were divided in 4 chronologically consecutive groups (G1, G2, G3, G4). Intraoperative characteristics and short term results were evaluated. Results: The mean velocity and the mean time of harvesting in G4 were 0,68 cm/min and 45 min. respectively, similar to the time required for a scheletonized left internal mammary artery harvesting. In the first 5 patients 2 conversions were required, one of them related to the EVH technique. No bleeding, functional impairment or infective complications are reported. Active mobilization was possible in every case in the first post-operative day. Conclusions: EVH is a reliable technique and the learning curve can be limited to the first 5 cases. The foreseeble reduction of infectious complications, the absence of pain and the immediate mobilization of the leg allow a rapid and effective rehabilitation.

scholarly journals Active control of multiscale features in wall-bounded turbulence

2019 ◽  
Vol 36 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Xiaotong Cui ◽  
Nan Jiang ◽  
Xiaobo Zheng ◽  
Zhanqi Tang
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulent Energy ◽  
Streamwise Velocity ◽  
Discrete Wavelet ◽  
Wall Region ◽  
Mean Velocity ◽  
Pzt Actuator ◽  
The Impact ◽  
Near Wall

Abstract This study experimentally investigates the impact of a single piezoelectric (PZT) actuator on a turbulent boundary layer from a statistical viewpoint. The working conditions of the actuator include a range of frequencies and amplitudes. The streamwise velocity signals in the turbulent boundary layer flow are measured downstream of the actuator using a hot-wire anemometer. The mean velocity profiles and other basic parameters are reported. Spectra results obtained by discrete wavelet decomposition indicate that the PZT vibration primarily influences the near-wall region. The turbulent intensities at different scales suggest that the actuator redistributes the near-wall turbulent energy. The skewness and flatness distributions show that the actuator effectively alters the sweep events and reduces intermittency at smaller scales. Moreover, under the impact of the PZT actuator, the symmetry of vibration scales’ velocity signals is promoted and the structural composition appears in an orderly manner. Probability distribution function results indicate that perturbation causes the fluctuations in vibration scales and smaller scales with high intensity and low intermittency. Based on the flatness factor, the bursting process is also detected. The vibrations reduce the relative intensities of the burst events, indicating that the streamwise vortices in the buffer layer experience direct interference due to the PZT control.

scholarly journals Balance Tests in Pre-Adolescent Children: Retest Reliability, Construct Validity, and Relative Ability

2020 ◽  
Vol 17 (15) ◽  
pp. 5474
Author(s):  
Vedrana Sember ◽  
Janja Grošelj ◽  
Maja Pajek
Keyword(s):  
Construct Validity ◽  
Mean Amplitude ◽  
Body Sway ◽  
Mean Velocity ◽  
Eyes Closed ◽  
Relative Ability ◽  
Balance Tests ◽  
Balance Ability ◽  
The Mean ◽  
The Impact

Balance is an essential prerequisite for the normal physical development of a child. It consists of the ability to maintain the body’s centre of mass over its base of support, which is enabled by automatic postural adjustments, and maintain posture and stability in various conditions and activities. The present study aimed to determine the measurement characteristics (reliability and concurrent validity) and the relative ability of balance tests and different motor tests in healthy 11-year-olds. We also evaluated the impact of vision on balance ability. Our results showed high interrater reliability (from 0.810 to 0.910) and confirmed the construct validity of the included balance tests. Girls performed significantly better than boys in laboratory tandem stance in following balance components: total sway path with eyes open (BSEO) (t = 2.68, p = 0.01, effect size (ES) = 0.81), total body sway with eyes closed of centre of pressure (CoP) displacement in the a-p direction (BSEC) (t = 1.86, p = 0.07, ES = 0.57), mean velocity of CoP displacements (VEO) (t = 2.67, p = 0.01, ES = 0.83), mean amplitude of CoP displacements in the a-p direction (AapEO) (t = 3.38. p = 0.00, ES = 1.01) and in mean amplitude of CoP displacements in the m-l direction (AmlEO) (t = 3.68, p = 0.00, ES = 1.19). With eyes closed, girls performed significantly better (t = 2.28, p = 0.03, ES = 0.70) than boys did in the mean amplitude of COP displacements in the a-p direction (AapEO) and significantly better (t = 2.37, p = 0.03, ES = 0.71) in the mean amplitude of COP displacements in the m-l direction (AmlEC). Insignificant correlations between different balance tests, except for a correlation between the flamingo test and one-leg stance on a low beam (r = 0.558, p < 0.01), show that each test assesses different aspects of balance ability; therefore, balance cannot be assessed with a single test.

Experimental study on longitudinal mixing in open channel flow with various vegetation patterns

2020 ◽  
Author(s):  
Hyoungchul Park ◽  
Jinhwan Hwang
Keyword(s):  
Shear Flow ◽  
Dispersion Coefficient ◽  
Longitudinal Dispersion ◽  
Velocity Shear ◽  
Vegetation Patterns ◽  
Longitudinal Dispersion Coefficient ◽  
Mean Velocity ◽  
Natural Streams ◽  
Longitudinal Mixing ◽  
The Impact

&lt;p&gt;In natural streams, vegetation considerably has an influence on the flow characteristics in a variety of ways. For example, vegetation distorts flow structure in both lateral and vertical directions and changes the magnitude of turbulence and shear flow. Due to these effects, diluted contaminants in river transport and disperse differently. Accordingly, many previous researchers have investigated the impact of vegetation on the mixing process. Most of them have estimated the dispersion coefficient since this is the crucial parameter to quantify the degree of dispersion of contaminants numerically. They mainly studied in diverse characteristics of vegetation, such as density or submergence, etc., and identified the change in hydraulic parameters involving the dispersion coefficient.&lt;/p&gt;&lt;p&gt;In this work, considering the vegetation distributed in various forms in the natural river, we studied the effect of vegetation patterns on the longitudinal mixing coefficient. Six types of spatial patterns considered in this study are represented numerically by introducing the standardized Morisita index. Laboratory experiments with artificial emergent vegetation were performed in multiple vegetation patterns, and the longitudinal dispersion coefficient was estimated from the measured concentration curves by applying the routing technique. And we analyzed the cause of change in dispersion coefficient by calculating not only the dispersion coefficient but also the magnitude of mean velocity, shear flow, turbulence, etc.&lt;/p&gt;&lt;p&gt;According to the experimental results, the mean velocity in the vegetated channel is almost the same regardless of the type of pattern but is always lower than that in the non-vegetated channel. The longitudinal dispersion coefficient gets larger as the arrangement changes from uniform to 2D clumped pattern. The cause of change in coefficient is closely related to the spatial velocity gradients in both lateral and vertical directions since the spatial heterogeneity of velocity increases the magnitude of shear flow.&lt;/p&gt;

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